GHz broadband power amplifier (PA) for high-resolution FMCW radars is presented in this paper. For bandwidth (BW) expanding, a Gm compensator-based negative feedback chain is applied to the PA, compensating the large gain ripple caused by a high-k transformer (TF)-based ultra-wideband interstage matching network (IMN). Based on the proposed Gm-compensated technique, a flat and ultra-wideband power gain of the PA can be obtained with the high-k TF-based IMN. The proposed PA achieves a 55-GHz BW without additional area overhead and efficiency loss. 74.8% of the fractional BW is obtained with <0.3 dB gain ripple in 53-92 GHz. The PA reaches 17.1 dBm Psat and 27% peak PAE respectively, and the core area of the proposed PA in TSMC 40nm CMOS process is 0.1mm 2 .
A Quadrature/Polar hybrid digital transmitter architecture (HB-TX) is proposed in this paper, which consists of a main digital power amplifier (DPA), an auxiliary DPA, and a low-bit phase selector. In the proposed HB-TX, coarse polar modulation is realized by combining the main DPA and a low-bit selector, while a fine quadrature modulation is realized by the asymmetrical quadrature recombination of main and auxiliary DPAs in a small range. Through coarse and fine modulation, the HB-TX realizes fast signal modulation and does not require high-speed and high-resolution phase modulator. With the coarse polar modulation, the HB-TX achieves high efficiency which is close to that of polar transmitter and no longer suffers from 3 dB back-off. Since the asymmetry of two-path DPA arrays improves the isolation between two channels, local oscillators (LOs) with 50% duty cycle is employed to further improve the HB-TX's efficiency. Simulation results show that the HB-TX with a 4-bit selector achieves 23.7-dBm peak output power with 39.2% peak power added efficiency (PAE). When modulating a 64-QAM signal with 80-Msym/s symbol rate and 6.5-dB peak average power rate (PAPR), the HB-TX improves the average drain efficiency from 16.3% (achieved in quadrature transmitter) to 22.2%. The average output power that is delivered by the HB-TX is 17.6-dBm with 17.4% average PAE, while the error vector magnitude (EVM) is -35.87 dB.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.